This invention relates to a cold drawing apparatus adapted to, in a process for making a fibrous web, cool and draw a plurality of melt spun filaments.
Japanese Patent Application Disclosure No. 1995-109658 describes a process for making a patterned fibrous web comprising a spinning step of discharging a plurality of continuous filaments from a spinning nozzle extending transversely of an apparatus onto a collecting conveyor travelling below the spinning nozzle to form the patterned fibrous web on the conveyor. An apparatus for static filamentation participates in the spinning step.
The apparatus for static filamentation is adapted to charge the filaments with static electricity so that these charged filaments may be spaced one from another under a repulsion generated among them. The filaments may be charged with electricity over a desired width, for a desired period and at a desired voltage in accordance with a predetermined program to provide the fibrous web with a predetermined pattern.
The process described in the Japanese Patent Application Disclosure No. 1995-109658 requires the apparatus for static filamentation adapted to a command from a programmed computer and thereupon to apply the filaments with voltage. Use of such apparatus for static filamentation correspondingly increases a manufacturing cost of the fibrous web.
This invention aims to provide a cold drawing apparatus requiring no apparatus for static filamentation to charge the filaments with static electricity and thereby enabling a patterned fibrous web to be made at a relatively low cost.
According to this invention, there is provided a cold drawing apparatus interposed in a system for making a fibrous web and having an inlet for a plurality of melt spun continuous filaments, an outlet for the filaments and a pair of side walls extending between the in- and outlets and opposed to and spaced from each other in a transverse direction orthogonal to a direction in which the filaments are fed to define a passage therebetween so that the filaments are cooled and drawn as the filaments pass through the passage defined between the opposed side walls, wherein: at least one of the opposed the walls is formed with a plurality of crests extending in the transverse direction at predetermined intervals and a plurality of troughs each extending between each pair of adjacent the crests.
In one preferred embodiment of this invention, the crests are formed on both of the side walls at regular intervals in the transverse direction so that the crests on one of the side walls are respectively opposed to the crests on the other side walls and wherein the troughs are formed on both of the side walls at regular intervals in the transverse direction so that the troughs respectively extend in fan shapes and the troughs on one of the side walls are respectively opposed to the troughs on the other side wall.
In another embodiment of this invention, a value corresponding to the minimum dimension of the passage defined between each pair of the opposed crests divided by the minimum dimension of the passage defined between each pair of the opposed troughs is in a range of 0.1xcx9c0.7.
In still another embodiment of this invention, a dimension of the crest as measured in the transverse direction is in a range of 10-100 mm and a dimension of the trough as measured in the transverse direction is in a range of 10xcx9c100 mm.
In further another embodiment of this invention, at least one of the side walls is formed with an air supply opening lying between the inlet and a region having the crests and troughs to supply compressed air toward the outlet.
In further additional embodiment of this invention, the apparatus is adapted to be oscillated in the transverse direction.